Although previous studies addressed this original way of how deducing past climate conditions from color paintings, such as aerosol optical depth (AOD) the new results are critically reviewing these former publications and yield new critical elements in this original research. While concluding that reconstructions of AOD may be possible in some specific cases, the authors do warn about the strong uncertainties related to parameters not carefully considered, which restrains the field of possibilities. To assess the scientific soundness of the results, three reviewers from complementary fields of atmospheric sciences positively reviewed the original manuscript. They have contributed to improve the quality of this paper and all agreed upon the conclusions research, which is a fair guarantee that these results should broadly interest the geoscience community.

Causes for the Great Oxidation Event (GOE) has long been an outstanding question in Earth sciences. Yet, the exploration of this question has been limited to the 1D photochemical models. Here, the authors presented new insights to solve this question with a 3D photochemical-climate model. This model allows the investigation of influences of the atmospheric circulation on the GOE and the coupling between the climate and the dynamics of the oxidation. The results are highly interesting, and would be of wide interest in Earth science community.